Simulated Failures - G1000

Itchy said:
An STC *would* be required. But I ask again: why even bother. THEY DIM?????
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Why would an STC be required? You are removing one component and replacing it with another, FAA approved, component of identical function. Would most certainly not (at least in my opinion, barring any existing FAA legal interpretation to the contrary) constitute a "change to the basic design of the electrical system", making it a minor alteration, thereby requiring no STC. And why bother? Because simply dimming one screen is a crappy way of simulating the failures of various individual boxes in the system. For example, in the 172 installation of the G1000, if you actually kill the AHRS, your ground track will continue to display on the moving map. However, after about 2 minutes that ground track will freeze and cease to be accurate. At least one flight school I am familiar with taught as SOP for an AHRS/ADC failure to use the ground track on the moving map to monitor the effectiveness of your heading corrections. THAT DOESN'T WORK IN REAL LIFE and that is the sort of thing that I think might be pretty damn important to know, don't you?
 
Eh...Yes? Did not really consider that failure, just the display itself.
Back to the STC. I thought if you changed part numbers, you were in new territory.
 
Itchy said:
Eh...Yes? Did not really consider that failure, just the display itself.
Back to the STC. I thought if you changed part numbers, you were in new territory.
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That's not what 14 CFR part 43 says.
http://ecfr.gpoaccess.gov/cgi/t/tex...w=text&node=14:1.0.1.3.21.0.363.14.52&idno=14
The above link describes major alterations. Anything that is not a major alteration, need only be done in accordance with acceptable data, I.e, no STC or form 337 required. The only exception to that is if someone owns an STC for what would otherwise be a minor alteration. In that case, legally, to reproduce said alteration, you must buy the STC. It's a form of patent protection.
 
Roger Roger said:
You mean like a pullable circuit breaker? The mechanical action is different, but the function is exactly the same.

Have seen many aircraft with switch breakers in place of regular breakers for EFIS components. Don't know that an FAA inspector would have a legal leg to stand on. That doesn't mean they wouldn't throw a fit, but you know as well as I do that FAA inspectors throw fits about all kinds of things that are perfectly legal.

I also don't think anyone really cares enough to actually do it. Those who would want to, will probably just pull the circuit breaker and replace it for 20 bucks after 10k cycles or whatever when it stops latching, and those who care enough to not pull circuit breakers would worry themselves about putting in a switch breaker. It's an interesting thought though, at least to me.
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Is the part approved for installation in the specified aircraft? FAR 43 App. A (4) Appliance Major Alterations. Alterations of the basic design not made IAW recommendations of the appliance manufacturer..."
You can not just go around replacing parts (including CBs), in FAR 23 aircraft with what ever parts you want to use withtout having them approved IAW FAR 21. Doing so results in more than just FAA certification action.
http://roseville-ca.patch.com/articles/six-allegedly-used-unapproved-parts-in-aircraft-repairs
It is the same reason you can not use the alternator from Autozone in your FAR 23 airplane while having it comply with its type certificate.
 
Replacing a circuit breaker is an alteration to the airframe, not to an appliance, so the part of the FARs you quoted does not apply to this conversation. Part 21 pretty clearly allows the installation of standard parts (i. e, mil spec switch breakers) on certificated aircraft. That, as far as I can tell, makes the part as legal to go on the aircraft as any nut, bolt, or spool of wire you can get from spruce. Putting a TSOd or mil spec switch breaker into a Cessna is a whoooole different ball of wax than using a paperclip to repair a Gulfstream part. The fact that you are replacing the original style of circuit breaker with one of the same rating and function should make it a minor alteration, requiring no STC/337.
 
To go even further with what Roger Roger was saying, many discrete (non-programmable) electrical components dont even need to be PMA'd per Docket No. AIR-100-96-01 where the FAA says electronic components are a good example of the exceptions in 21.303(b)(4). That's getting a bit out of the scope, but it illustrates the point that there is some liberty in making some changes to certified aircraft.
 
rframe said:
To go even further with what Roger Roger was saying, many discrete (non-programmable) electrical components dont even need to be PMA'd per Docket No. AIR-100-96-01 where the FAA says electronic components are a good example of the exceptions in 21.303(b)(4). That's getting a bit out of the scope, but it illustrates the point that there is some liberty in making some changes to certified aircraft.
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I know a guy who fixed a piston airplane annunciator panel with a diode from radio shack. Still going strong last I heard...
 
This thread makes me lol. I blew a half dozen circuit breakers on the metro a couple weeks ago, I made sure to call my FSDO in air to get the STC.
 
I bought some of those little plastic things that stuck on via static electricity or other magic that looked like the little failed component that is displayed on the PFD.

Sent from my SPH-D700 using Tapatalk
 
Roger Roger said:
Replacing a circuit breaker is an alteration to the airframe, not to an appliance, so the part of the FARs you quoted does not apply to this conversation. Part 21 pretty clearly allows the installation of standard parts (i. e, mil spec switch breakers) on certificated aircraft. That, as far as I can tell, makes the part as legal to go on the aircraft as any nut, bolt, or spool of wire you can get from spruce. Putting a TSOd or mil spec switch breaker into a Cessna is a whoooole different ball of wax than using a paperclip to repair a Gulfstream part. The fact that you are replacing the original style of circuit breaker with one of the same rating and function should make it a minor alteration, requiring no STC/337.
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1. The question I responded to was about installing a switch that would control the failure modes of the G1000. Put in a separate switch to control the G1000 failure modes and it most definitely will require an STC.
2. Even if the circuit switch you talk about is approved for aviation use it may, or may not be permissible to use it in particular aircraft. For example, if a certain item requires a slow blo fuse you can not decide on your own to use another type of fuse. Without looking at the specific parts in question and the actual aircraft application it is difficult to make a blanket statement. Aircraft have been brought down by mechanics using the wrong size bolts. The bolts were mil spec... just the wrong type.
So again, the specific question was about installing an on/off switch to replicate G1000 failures. Installing such a specific switch would most likely require an STC.
Could one replace the installed CB with the type you discuss? Possibly, but a mechanic would need to look at the specific application.
 
Roger Roger said:
Further reading on standard parts...
http://www.faa.gov/aircraft/safety/programs/sups/standard_parts/media/62fr9923.txt
http://www.faa.gov/aircraft/safety/programs/sups/standard_parts/media/standard_parts.pdf
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From your first reference:
"Generally, a standard part may be replaced with an identical standard part, in accordance with the manufacturers maintenance instructions, without a further demonstration of compliance with the airworthiness regulations. Substitution of a standard part with another would require a demonstration of acceptability in accordance with part 43."

If you are installing a different type of CB it is not "identical" and would require a demonstration of acceptability.
 
This. (I would have the hash mark pointing at the post above but on a Droid.) So small G1000 installs do not use dual ahars/adc's?
 
Blackhawk said:
From your first reference:
"Generally, a standard part may be replaced with an identical standard part, in accordance with the manufacturers maintenance instructions, without a further demonstration of compliance with the airworthiness regulations. Substitution of a standard part with another would require a demonstration of acceptability in accordance with part 43."

If you are installing a different type of CB it is not "identical" and would require a demonstration of acceptability.
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Right, and based on the AC43.13 (acceptable data) section on electrical wiring, I bet you would find that a breaker switch is, in fact, acceptable. For the record, if you go back to my original post, I never advocated installing a separate switch, just replacing the existing breaker with a switchable one. I'm not sure what your involvement level with maintenance is, or why you're so wrapped up in this when I'm fairly sure you don't deal with this stuff on a daily basis, but you'll find that the FAA does, in fact, give a mech quite a bit of freedom in creating minor alterations, using approved parts, in accordance with AC43.13. Here is another example- per at least one FSDO, you can replace a standard landing light with a LED one with simply a logbook entry, provided the electrical load analysis and the existing wire size accommodate it because, once again, you are replacing a standard electrical part with one of the same functionality, using approved parts. Note that this mod often does actually require and STC because the maker of the LED lights owns an STC for their installation.
Itchy said:
So small G1000 installs do not use dual ahars/adc's?
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Nope. The ones I have experience with (172, DA42) do not. I believe the Cirrus install does though.
 
Roger Roger said:
Right, and based on the AC43.13 (acceptable data) section on electrical wiring, I bet you would find that a breaker switch is, in fact, acceptable. For the record, I never advocated installing a separate switch, just replacing the existing breaker with a switchable one. I'm not sure what your involvement level with maintenance is, or why you're so wrapped up in this when I'm fairly sure you don't deal with this stuff on a daily basis, but you'll find that the FAA does, in fact, give a mech quite a bit of freedom in creating minor alterations, using approved parts, in accordance with AC43.13. Here is another example- per at least one FSDO, you can replace a standard landing light with a LED one with simply a logbook entry, provided the electrical load analysis and the existing wire size accommodate it because, once again, you are replacing a standard electrical part with one of the same functionality, using approved parts. Note that this mod often does actually require and STC because the maker of the LED lights owns an STC for their installation.

Nope. The ones I have experience with (172, DA42) do not.
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Do not, I repeat, do not necessarily go with just what a FSDO says. If they point you in the right direction and what you do is supported by regulation, great. If it is only supported by a FSDO interpretation, however, you could find yourself in violation of regulations without a paddle. I'm not saying installing the LEDs is right or wrong, just saying that one should not just go with just the FSDO interpretation. I do notice that when one looks at these as replacements you see "TSO..." which leads me to believe they are approved in most cases as replacements for existing bulbs.
I do deal with it on a daily basis as a pilot and I am wrapped up in the stuff because "my mechanic said it is okay" does not protect you when the FAA comes knocking (see FAA v. Nielson), or, even worse, if proper procedures are not followed or proper parts installed. As a recent example I noticed while preflighting a 182 that the CHT was placarded inop- even though it is required for flight in all airplanes with cowl flaps. The mechanic had no idea this was the case.
Now again, I'm not necessarily saying one is wrong or right for changing the type of circuit breaker you discuss. Using the reference you provided, however, it is not an identical part. One would really need to look at the specific airplane and the parts being interchanged. Making a blanket statement that what is acceptable in one airplane works in all is not necessarily the case.
 
trafficinsight said:
A circuit breaker is a circuit breaker, no matter how you actuate it.


Sent from 1865 by telegraph....
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Yet he is calling the replacement he will use something different- a circuit switch. These leads me to believe there IS a difference, though I admit I am not an expert.
 
Blackhawk said:
Making a blanket statement that what is acceptable in one airplane works in all is not necessarily the case.
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if that is what I conveyed, then I miscommunicated. I am simply saying that it is my belief that, in fact, the particular modification I originally proposed, would be legal.
Blackhawk said:
Yet he is calling the replacement he will use something different- a circuit switch. These leads me to believe there IS a difference, though I admit I am not an expert.
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Well, now this is another matter. Breaker switches are sold as circuit breakers, and one surmises that they may, in fact, be subject to the same wear out as a pullable breaker. So maybe my idea isn't so brilliant. However, for that matter, even plain jane switches wear out eventually. I've changed many of them (always, of course, with FAA approved parts).
 
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